A89: AMS 2.05 and ASM

I have read through the archive of old messages to
the list about AMS 2.05 problems with shells and asm programs. I have also read
other pages on problems with the new AMS and they said that you couldnt
downgrade AMS 2.05 to a lower version if it was released with version 2.05. I
just wanted to make sure that this information was wrong and that it does work
before I buy a TI89. More than likely the only ones available will be version
2.05 and the reason I'm getting one is so I can program in asm and enjoy the
extras that everyone has made for the calculator. Also I read in the list
archive that there is supposedly a version of the doors kernel that can run
right on 2.05 but does that allow the programs to install and run on it also?
Thanks for any help in advance.